Activating/deactivating lots of gameobject at the same time

Hello everyone, i'm Gabriel

I'm currently wortking on a base building game (dwarf Fortress-like) and i have a problem with big maps. I'm not very used to unity but i did this using tutorials and so far eveything was going on quite well.

The at first i used a 16*16*16 map and everything worked well. But now that i add depth and scale (64*64*64), i am encountering some problems.

I render only one layer of my map (4096 gameobjects). Those layers are composed of cubes. One cube is a game object with a script attached, and 6 children , each of them being a quad (meshfilter+mesh renderer + a material from 32*32px texture) with a meshCollider (used for clicking on the tile). Those gameobjects are static, and all cube from a layer are attached to an empty GO.

hierarchy :

-WorldManager

------- layer_0

------------------tile_0_0_0

------------------tile_0_0_1

------------------tile_0_0_1

------------------+4093 others

------- layer_1

------------------tile_0_1_0

------------------+ 4095 others

------- + 62 other layers

etc

When i change the level, i deactivate one layer gameobject and activate another, while ckecking for tiles that could have changed, with this code :

 tileGOCS[64,64,64] : gameobjectController array
 tileGOCSparents[64] : layer array
 
         // deactivate level from
         tileGOCSparents[YlevelFrom].SetActive(false);
 
         // actiavte level we go to if it exists
         if (tileGOCSparents[YlevelTo] != null) tileGOCSparents[YlevelTo].SetActive(true);
         // else create it
         else {
             GameObject parent = new GameObject("TileLayer_" + YlevelTo);
             parent.isStatic = true;
             parent.transform.SetParent(this.transform);
             tileGOCSparents[YlevelTo] = parent;
         }
 
         // check for tile without object
         for (int x = 0; x < tileGOCs.GetLength(0); x++) {
             for (int z = 0; z < tileGOCs.GetLength(0); z++) {
                 if (tileGOCs[x, YlevelTo, z] == null) {
                     Tile t = Ref.world.GetTileAt(x, YlevelTo, z);
                     CreateTileGO(t);
                 }
             }
         }

And it takes a little less than one second to change between levels. And i would like to show at least 3 levels for depth percpetion. So my questions are : - are 4000 go too much for unity to handle? - are my gameobjects to computer-heavy? i tried removing the colliders but it changed little - i have an up-to-date computer so i don't think it's a question of hardware but optimization

Thanks in advance for yours answers. Feel free to ask me details about that.